X-ray analysis of samples is a growing area of interest across many industries such as medical, pharmaceutical, and petroleum. U.S. Pat. Nos. 6,934,359 and 7,072,439, incorporated by reference herein in their entirety and assigned to X-Ray Optical Systems, Inc., the assignee of the present invention, disclose monochromatic wavelength dispersive x-ray fluorescence (MWD XRF) techniques and systems for the analysis of liquid samples. As one particular example, these patents disclose techniques for the determination of the level of sulfur in petroleum fuels, and a commercialized analyzer (SINDIE) is now in widespread use for this measurement at petroleum refining, pipeline, and terminal facilities.
Sample handling is of critical importance in such systems, as is x-ray shielding. It is a general requirement of bench-top x-ray analysis systems to minimize x-ray exposure during sample loading and unloading. Traditionally, this is accomplished by interlock systems which mechanically and/or electrically control an x-ray blocking “shutter” mechanism over the x-ray source. An interlock system senses an operator opening the system to load/unload a sample, and automatically activates the shutter to completely block any x-rays from transmitting through the now-open sample door, toward an operator. Implementation of shutter mechanisms can be complex and costly, therefore, there is a need for a sample insertion and removal system which simplifies the x-ray interlock and/or shutter requirements.
Moreover, any sample insertion and removal technique must also present the sample to the x-ray measurement engine at a precise distance (along a z-axis as discussed below) for proper alignment to the requisite x-ray analysis spot. This z-axis alignment is critically important for x-ray optic enabled analyzers (such as those disclosed in the above-incorporated U.S. Patents and discussed further below) because of the sensitivity of the measurement to the focal spots of one or two separate optics in the x-ray excitation and/or detection paths.
What is required, therefore, is a sample insertion and removal apparatus, which minimizes x-ray leakage and simplifies x-ray shutter design, and which provides precise alignment of a sample to an x-ray analyzer engine, especially an x-ray optic-enabled analyzer engine.